/*
 * Copyright (C) 2012 The Guava Authors
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package jmind.core.algo.atomic;

import java.util.concurrent.atomic.AtomicLong;

/**
 * Source of {@link jmind.core.algo.atomic.LongAddable} objects that deals with GWT, Unsafe, and all
 * that.
 *
 * @author Louis Wasserman
 */
public final class LongAddables {
    private static final Supplier<LongAddable> SUPPLIER;

    static {
        Supplier<LongAddable> supplier;
        try {
            new LongAdder();
            supplier = new Supplier<LongAddable>() {
                @Override
                public LongAddable get() {
                    return new LongAdder();
                }
            };
        } catch (Throwable t) { // we really want to catch *everything*
            supplier = new Supplier<LongAddable>() {
                @Override
                public LongAddable get() {
                    return new PureJavaLongAddable();
                }
            };
        }
        SUPPLIER = supplier;
    }

    public static LongAddable create() {
        return SUPPLIER.get();
    }

    private static final class PureJavaLongAddable extends AtomicLong implements LongAddable {
        @Override
        public void increment() {
            getAndIncrement();
        }

        @Override
        public void add(long x) {
            getAndAdd(x);
        }

        @Override
        public long sum() {
            return get();
        }
    }

    private static interface Supplier<T> {

        T get();

    }

}
